This invention relates to a gas bag module cover and to a vehicle steering wheel provided with a gas bag module cover according to the invention.
In a restraint situation, a cover of a gas bag module is torn up by the deploying gas bag or by some other means and is intended to release the initially closed outlet opening as quickly as possible. The swiveling radius of the opening portion should be rather small here, in order to minimize the risk for the occupant to be hit by the opening portion swiveling towards outside. While there is no risk for occupants having the ideal sitting position, occupants might for instance lean against the dashboard or the steering wheel and be hit by the opening portion swiveling towards outside in the case of restraint.
The invention provides a gas bag module cover which distinctly reduces the risk of injury originating with the opening portion. This is achieved in a gas bag module cover which comprises at least one opening portion for closing an outlet opening, and a predetermined tear line along which the cover is opened in a restraint situation and which defines the at least one opening portion of the cover. The gas bag module further comprises at least one first hinge portion provided on the cover, via which first hinge portion the opening portion, when said cover is opened, remains connected with the cover. The opening portion has at least one second hinge portion which divides the opening portion into partial sections and allows a relative movement of the partial sections. By means of the second hinge portion, which divides the opening portion, the stability of the opening portion is reduced after the cover has been opened, as the second hinge portion allows partial sections to move relative to each other, i.e. to preferably be swiveled towards each other. Hence it is possible that the radius of movement of the opening portion is reduced. The opening portion can be kinked about the second hinge portion, which is for instance caused by the deploying gas bag, the partial sections thus swivel towards each other, and in this kinked or partly kinked condition the opening portion will then move towards outside. A further advantage of the invention consists in that the opening portion, which forms a flap, may indeed partly be directed towards the occupant upon deployment of the gas bag and possibly upon deflation of the gas bag after the accident, but in the case of a secondary impact, where the occupant gets in contact with the opening portion, causes no injuries due to its low stability. The stability, above all against kinking, is decreased by the second hinge portion. Moreover, in the open condition of the opening portion, the partial sections are not aligned parallel to each other, so that a force exerted on the edge defining the outer end of the opening portion can be very small in order to kink the opening portion.
Preferably, the first and the second hinge portion extend parallel to each other, so as not to exert any torsional forces on the opening portion.
Hinge portions may be formed by film hinges, i.e. by portions of the gas bag module cover with a reduced thickness, which reduces the manufacturing costs.
In accordance with one aspect, the cover according to the invention also has a front wall and a side wall, which is common practice particularly with covers for steering wheel gas bag modules. In this embodiment, the first hinge portion is provided in the side wall. Due to this position of the first hinge portion, the opening portion will move less far towards the occupant than in an embodiment in which the first hinge portion is provided at the front wall.
When the hinge portions offers different resistances to a swivel movement of the portions of the cover pivotally mounted at the same and/or different resistances in the possible opposite swiveling directions, the path of movement of the individual partial sections when the cover is opened can be influenced such that for instance the opening portion is kinked in the first opening phase, before the opening portion as a whole is completely swiveled to the outside. The positions of the hinge portions and possibly the opening behavior of the gas bag may also influence the course of the opening process.
The cover according to the invention may be suitable for any kind of module cover, either for side gas bag modules, passenger modules, in which case the cover is part of the dashboard, or for driver-side steering wheel modules.
The invention also relates to a vehicle steering wheel comprising a steering wheel rim, a gas bag module as well as a cover according to the invention. The position of the first and the second hinge portions and the position of the tear line are coordinated with the steering wheel rim such that the opening portion can swivel to axially behind the steering wheel rim, so that in the fully open condition of the cover the opening portion is positioned as far away from the occupant as possible.
To prevent the opening portion from swiveling back, the hinge portions are coordinated with each other such that upon axially swiveling to behind the steering wheel rim, the opening portion is prevented from swiveling back by the steering wheel rim itself, which in this case acts as stop.